Policy-based access in a dispersed storage network

ABSTRACT

A method for execution by a dispersed storage and task (DST) execution unit operates to receive a slice retrieval request from a requester that includes a slice name of one or slices to be retrieved; determine an access policy to apply to the slice retrieval request; determine a timestamp; and determine, based on the timestamp, when the one or more slices are available for retrieval. When the one or more slices are available for retrieval, the method operates further to determine when the one or more slices are currently available to the requester; retrieves the one or more slices from memory and sends the one or more slices to the requester, when the one or more slices are currently available to the requester.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present U.S. Utility patent application claims priority pursuant to35 U.S.C. §120 as a continuation-in-part of U.S. Utility applicationSer. No. 14/612,422, entitled “TIME BASED DISPERSED STORAGE ACCESS”,filed Feb. 3, 2015, which is a continuation of U.S. Utility applicationSer. No. 12/886,368, now issued as U.S. Pat. No. 8,990,585, entitled“TIME BASED DISPERSED STORAGE ACCESS”, filed Sep. 20, 2010, issued Mar.24, 2015, which claims priority pursuant to 35 U.S.C. §119(e) to U.S.Provisional Application No. 61/290,757, entitled “DISTRIBUTED STORAGETIME SYNCHRONIZATION”, filed Dec. 29, 2009, all of which are herebyincorporated herein by reference in their entirety and made part of thepresent U.S. Utility patent application for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

This invention relates generally to computer networks and moreparticularly to dispersing error encoded data.

2. Description of Related Art

Computing devices are known to communicate data, process data, and/orstore data. Such computing devices range from wireless smart phones,laptops, tablets, personal computers (PC), work stations, and video gamedevices, to data centers that support millions of web searches, stocktrades, or on-line purchases every day. In general, a computing deviceincludes a central processing unit (CPU), a memory system, userinput/output interfaces, peripheral device interfaces, and aninterconnecting bus structure.

As is further known, a computer may effectively extend its CPU by using“cloud computing” to perform one or more computing functions (e.g., aservice, an application, an algorithm, an arithmetic logic function,etc.) on behalf of the computer. Further, for large services,applications, and/or functions, cloud computing may be performed bymultiple cloud computing resources in a distributed manner to improvethe response time for completion of the service, application, and/orfunction. For example, Hadoop is an open source software framework thatsupports distributed applications enabling application execution bythousands of computers.

In addition to cloud computing, a computer may use “cloud storage” aspart of its memory system. As is known, cloud storage enables a user,via its computer, to store files, applications, etc. on an Internetstorage system. The Internet storage system may include a RAID(redundant array of independent disks) system and/or a dispersed storagesystem that uses an error correction scheme to encode data for storage.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an embodiment of a dispersed ordistributed storage network (DSN) in accordance with the presentinvention;

FIG. 2 is a schematic block diagram of an embodiment of a computing corein accordance with the present invention;

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data in accordance with the present invention;

FIG. 4 is a schematic block diagram of a generic example of an errorencoding function in accordance with the present invention;

FIG. 5 is a schematic block diagram of a specific example of an errorencoding function in accordance with the present invention;

FIG. 6 is a schematic block diagram of an example of a slice name of anencoded data slice (EDS) in accordance with the present invention;

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of data in accordance with the present invention;

FIG. 8 is a schematic block diagram of a generic example of an errordecoding function in accordance with the present invention;

FIG. 9 is a schematic block diagram of an embodiment of a dispersed ordistributed storage network (DSN) in accordance with the presentinvention;

FIGS. 10A-10C are schematic block diagrams of embodiments of a dispersedstorage network (DSN) memory storage sets; and

FIG. 11 is a flowchart illustrating an example of retrieving encodeddata slices.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram of an embodiment of a dispersed, ordistributed, storage network (DSN) 10 that includes a plurality ofcomputing devices 12-16, a managing unit 18, an integrity processingunit 20, and a DSN memory 22. The components of the DSN 10 are coupledto a network 24, which may include one or more wireless and/or wirelined communication systems; one or more non-public intranet systemsand/or public internet systems; and/or one or more local area networks(LAN) and/or wide area networks (WAN).

The DSN memory 22 includes a plurality of storage units 36 that may belocated at geographically different sites (e.g., one in Chicago, one inMilwaukee, etc.), at a common site, or a combination thereof. Forexample, if the DSN memory 22 includes eight storage units 36, eachstorage unit is located at a different site. As another example, if theDSN memory 22 includes eight storage units 36, all eight storage unitsare located at the same site. As yet another example, if the DSN memory22 includes eight storage units 36, a first pair of storage units are ata first common site, a second pair of storage units are at a secondcommon site, a third pair of storage units are at a third common site,and a fourth pair of storage units are at a fourth common site. Notethat a DSN memory 22 may include more or less than eight storage units36. Further note that each storage unit 36 includes a computing core (asshown in FIG. 2, or components thereof) and a plurality of memorydevices for storing dispersed error encoded data.

In various embodiments, each of the storage units operates as adistributed storage and task (DST) execution unit, and is operable tostore dispersed error encoded data and/or to execute, in a distributedmanner, one or more tasks on data. The tasks may be a simple function(e.g., a mathematical function, a logic function, an identify function,a find function, a search engine function, a replace function, etc.), acomplex function (e.g., compression, human and/or computer languagetranslation, text-to-voice conversion, voice-to-text conversion, etc.),multiple simple and/or complex functions, one or more algorithms, one ormore applications, etc. Hereafter, a storage unit may be interchangeablyreferred to as a dispersed storage and task (DST) execution unit and aset of storage units may be interchangeably referred to as a set of DSTexecution units.

Each of the computing devices 12-16, the managing unit 18, and theintegrity processing unit 20 include a computing core 26, which includesnetwork interfaces 30-33. Computing devices 12-16 may each be a portablecomputing device and/or a fixed computing device. A portable computingdevice may be a social networking device, a gaming device, a cell phone,a smart phone, a digital assistant, a digital music player, a digitalvideo player, a laptop computer, a handheld computer, a tablet, a videogame controller, and/or any other portable device that includes acomputing core. A fixed computing device may be a computer (PC), acomputer server, a cable set-top box, a satellite receiver, a televisionset, a printer, a fax machine, home entertainment equipment, a videogame console, and/or any type of home or office computing equipment.Note that each managing unit 18 and the integrity processing unit 20 maybe separate computing devices, may be a common computing device, and/ormay be integrated into one or more of the computing devices 12-16 and/orinto one or more of the storage units 36.

Each interface 30, 32, and 33 includes software and hardware to supportone or more communication links via the network 24 indirectly and/ordirectly. For example, interface 30 supports a communication link (e.g.,wired, wireless, direct, via a LAN, via the network 24, etc.) betweencomputing devices 14 and 16. As another example, interface 32 supportscommunication links (e.g., a wired connection, a wireless connection, aLAN connection, and/or any other type of connection to/from the network24) between computing devices 12 & 16 and the DSN memory 22. As yetanother example, interface 33 supports a communication link for each ofthe managing unit 18 and the integrity processing unit 20 to the network24.

Computing devices 12 and 16 include a dispersed storage (DS) clientmodule 34, which enables the computing device to dispersed storage errorencode and decode data as subsequently described with reference to oneor more of FIGS. 3-8. In this example embodiment, computing device 16functions as a dispersed storage processing agent for computing device14. In this role, computing device 16 dispersed storage error encodesand decodes data on behalf of computing device 14. With the use ofdispersed storage error encoding and decoding, the DSN 10 is tolerant ofa significant number of storage unit failures (the number of failures isbased on parameters of the dispersed storage error encoding function)without loss of data and without the need for a redundant or backupcopies of the data. Further, the DSN 10 stores data for an indefiniteperiod of time without data loss and in a secure manner (e.g., thesystem is very resistant to unauthorized attempts at accessing thedata). In various embodiments, computing devices 12-16 can include userdevices and/or can be utilized by a requesting entity generating accessrequests, which can include requests to read or write data to storageunits in the DSN.

In operation, the managing unit 18 performs DS management services. Forexample, the managing unit 18 establishes distributed data storageparameters (e.g., vault creation, distributed storage parameters,security parameters, billing information, user profile information,etc.) for computing devices 12-14 individually or as part of a group ofuser devices. As a specific example, the managing unit 18 coordinatescreation of a vault (e.g., a virtual memory block associated with aportion of an overall namespace of the DSN) within the DSN memory 22 fora user device, a group of devices, or for public access and establishesper vault dispersed storage (DS) error encoding parameters for a vault.The managing unit 18 facilitates storage of DS error encoding parametersfor each vault by updating registry information of the DSN 10, where theregistry information may be stored in the DSN memory 22, a computingdevice 12-16, the managing unit 18, and/or the integrity processing unit20.

The DSN managing unit 18 creates and stores user profile information(e.g., an access control list (ACL)) in local memory and/or withinmemory of the DSN memory 22. The user profile information includesauthentication information, permissions, and/or the security parameters.The security parameters may include encryption/decryption scheme, one ormore encryption keys, key generation scheme, and/or dataencoding/decoding scheme.

The DSN managing unit 18 creates billing information for a particularuser, a user group, a vault access, public vault access, etc. Forinstance, the DSN managing unit 18 tracks the number of times a useraccesses a non-public vault and/or public vaults, which can be used togenerate a per-access billing information. In another instance, the DSNmanaging unit 18 tracks the amount of data stored and/or retrieved by auser device and/or a user group, which can be used to generate aper-data-amount billing information.

As another example, the managing unit 18 performs network operations,network administration, and/or network maintenance. Network operationsincludes authenticating user data allocation requests (e.g., read and/orwrite requests), managing creation of vaults, establishingauthentication credentials for user devices, adding/deleting components(e.g., user devices, storage units, and/or computing devices with a DSclient module 34) to/from the DSN 10, and/or establishing authenticationcredentials for the storage units 36. Network administration includesmonitoring devices and/or units for failures, maintaining vaultinformation, determining device and/or unit activation status,determining device and/or unit loading, and/or determining any othersystem level operation that affects the performance level of the DSN 10.Network maintenance includes facilitating replacing, upgrading,repairing, and/or expanding a device and/or unit of the DSN 10.

The integrity processing unit 20 performs rebuilding of ‘bad’ or missingencoded data slices. At a high level, the integrity processing unit 20performs rebuilding by periodically attempting to retrieve/list encodeddata slices, and/or slice names of the encoded data slices, from the DSNmemory 22. For retrieved encoded slices, they are checked for errors dueto data corruption, outdated version, etc. If a slice includes an error,it is flagged as a ‘bad’ slice. For encoded data slices that were notreceived and/or not listed, they are flagged as missing slices. Badand/or missing slices are subsequently rebuilt using other retrievedencoded data slices that are deemed to be good slices to produce rebuiltslices. The rebuilt slices are stored in the DSN memory 22.

FIG. 2 is a schematic block diagram of an embodiment of a computing core26 that includes a processing module 50, a memory controller 52, mainmemory 54, a video graphics processing unit 55, an input/output (IO)controller 56, a peripheral component interconnect (PCI) interface 58,an 10 interface module 60, at least one IO device interface module 62, aread only memory (ROM) basic input output system (BIOS) 64, and one ormore memory interface modules. The one or more memory interfacemodule(s) includes one or more of a universal serial bus (USB) interfacemodule 66, a host bus adapter (HBA) interface module 68, a networkinterface module 70, a flash interface module 72, a hard drive interfacemodule 74, and a DSN interface module 76.

The DSN interface module 76 functions to mimic a conventional operatingsystem (OS) file system interface (e.g., network file system (NFS),flash file system (FFS), disk file system (DFS), file transfer protocol(FTP), web-based distributed authoring and versioning (WebDAV), etc.)and/or a block memory interface (e.g., small computer system interface(SCSI), internet small computer system interface (iSCSI), etc.). The DSNinterface module 76 and/or the network interface module 70 may functionas one or more of the interface 30-33 of FIG. 1. Note that the 10 deviceinterface module 62 and/or the memory interface modules 66-76 may becollectively or individually referred to as IO ports.

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data. When a computing device 12 or 16 has data tostore it disperse storage error encodes the data in accordance with adispersed storage error encoding process based on dispersed storageerror encoding parameters. Here, the computing device stores data object40, which can include a file (e.g., text, video, audio, etc.), or otherdata arrangement. The dispersed storage error encoding parametersinclude an encoding function (e.g., information dispersal algorithm,Reed-Solomon, Cauchy Reed-Solomon, systematic encoding, non-systematicencoding, on-line codes, etc.), a data segmenting protocol (e.g., datasegment size, fixed, variable, etc.), and per data segment encodingvalues. The per data segment encoding values include a total, or pillarwidth, number (T) of encoded data slices per encoding of a data segmenti.e., in a set of encoded data slices); a decode threshold number (D) ofencoded data slices of a set of encoded data slices that are needed torecover the data segment; a read threshold number (R) of encoded dataslices to indicate a number of encoded data slices per set to be readfrom storage for decoding of the data segment; and/or a write thresholdnumber (W) to indicate a number of encoded data slices per set that mustbe accurately stored before the encoded data segment is deemed to havebeen properly stored. The dispersed storage error encoding parametersmay further include slicing information (e.g., the number of encodeddata slices that will be created for each data segment) and/or slicesecurity information (e.g., per encoded data slice encryption,compression, integrity checksum, etc.).

In the present example, Cauchy Reed-Solomon has been selected as theencoding function (a generic example is shown in FIG. 4 and a specificexample is shown in FIG. 5); the data segmenting protocol is to dividethe data object into fixed sized data segments; and the per data segmentencoding values include: a pillar width of 5, a decode threshold of 3, aread threshold of 4, and a write threshold of 4. In accordance with thedata segmenting protocol, the computing device 12 or 16 divides dataobject 40 into a plurality of fixed sized data segments (e.g., 1 throughY of a fixed size in range of Kilo-bytes to Tera-bytes or more). Thenumber of data segments created is dependent of the size of the data andthe data segmenting protocol.

The computing device 12 or 16 then disperse storage error encodes a datasegment using the selected encoding function (e.g., Cauchy Reed-Solomon)to produce a set of encoded data slices. FIG. 4 illustrates a genericCauchy Reed-Solomon encoding function, which includes an encoding matrix(EM), a data matrix (DM), and a coded matrix (CM). The size of theencoding matrix (EM) is dependent on the pillar width number (T) and thedecode threshold number (D) of selected per data segment encodingvalues. To produce the data matrix (DM), the data segment is dividedinto a plurality of data blocks and the data blocks are arranged into Dnumber of rows with Z data blocks per row. Note that Z is a function ofthe number of data blocks created from the data segment and the decodethreshold number (D). The coded matrix is produced by matrix multiplyingthe data matrix by the encoding matrix.

FIG. 5 illustrates a specific example of Cauchy Reed-Solomon encodingwith a pillar number (T) of five and decode threshold number of three.In this example, a first data segment is divided into twelve data blocks(D1-D12). The coded matrix includes five rows of coded data blocks,where the first row of X11-X14 corresponds to a first encoded data slice(EDS 1_1), the second row of X21-X24 corresponds to a second encodeddata slice (EDS 2_1), the third row of X31-X34 corresponds to a thirdencoded data slice (EDS 3_1), the fourth row of X41-X44 corresponds to afourth encoded data slice (EDS 4_1), and the fifth row of X51-X54corresponds to a fifth encoded data slice (EDS 5_1). Note that thesecond number of the EDS designation corresponds to the data segmentnumber.

Returning to the discussion of FIG. 3, the computing device also createsa slice name (SN) for each encoded data slice (EDS) in the set ofencoded data slices. A typical format for a slice name 80 is shown inFIG. 6. As shown, the slice name (SN) 80 includes a pillar number of theencoded data slice (e.g., one of 1−T), a data segment number (e.g., oneof 1−Y), a vault identifier (ID), a data object identifier (ID), and mayfurther include revision level information of the encoded data slices.The slice name functions as, at least part of, a DSN address for theencoded data slice for storage and retrieval from the DSN memory 22.

As a result of encoding, the computing device 12 or 16 produces aplurality of sets of encoded data slices, which are provided with theirrespective slice names to the storage units for storage. As shown, thefirst set of encoded data slices includes EDS 1_1 through EDS 5_1 andthe first set of slice names includes SN 1_1 through SN 5_1 and the lastset of encoded data slices includes EDS 1_Y through EDS 5_Y and the lastset of slice names includes SN 1_Y through SN 5_Y.

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of a data object that was dispersed storage error encodedand stored in the example of FIG. 4. In this example, the computingdevice 12 or 16 retrieves from the storage units at least the decodethreshold number of encoded data slices per data segment. As a specificexample, the computing device retrieves a read threshold number ofencoded data slices.

To recover a data segment from a decode threshold number of encoded dataslices, the computing device uses a decoding function as shown in FIG.8. As shown, the decoding function is essentially an inverse of theencoding function of FIG. 4. The coded matrix includes a decodethreshold number of rows (e.g., three in this example) and the decodingmatrix in an inversion of the encoding matrix that includes thecorresponding rows of the coded matrix. For example, if the coded matrixincludes rows 1, 2, and 4, the encoding matrix is reduced to rows 1, 2,and 4, and then inverted to produce the decoding matrix.

FIG. 9 is a schematic block diagram of another embodiment of a dispersedstorage network (DSN) that includes a computing device 16 of FIG. 1, thenetwork 24 of FIG. 1, and a computing device 12, managing unit 18 orintegrity processing unit 20. The computing device 16 can include theinterface 32 of FIG. 1, the computing core 26 of FIG. 1, and the DSclient module 34 of FIG. 1. The computing device 16 can function as adispersed storage processing agent for computing device 14 as describedpreviously, and may hereafter be referred to as a distributed storageand task (DST) processing unit. The computing device 12, managing unit18 or integrity processing unit 20 can include the interface 32 or 33 ofFIG. 1, and the computing core 26 of FIG. 2.

The DSN functions to receive access requests from the computing device12, managing unit 18 or integrity processing unit 20, verify sliceavailability and to respond with access results that, for example,either include the requested slices or indicate that they areunavailable. In various embodiments, the whether or not the requestedslices are available is determined pursuant to an access policy. Theaccess policy may be previously determined by any one or more of a userdevice, a DS processing unit, a storage integrity processing unit, a DSmanaging unit, and another DS unit. In an example, the DS managing unit18 determines the access policy. The access policy may include a timevarying availability pattern of a DS unit, a pillar, and/or a vault. Forexample, the pattern indicates that vault 1 is available to any userfrom noon to midnight every day and is not available from midnight tonoon. In another example, the pattern indicates that pillar 2 of vault 3is available to any user from noon to midnight every day and is notavailable from midnight to noon. In another example, the patternindicates that pillar 2 of vault 3 is available only to user 5 from noonto midnight every day and is available to the DS managing unit 24 hoursa day. In an example, the DSN stores slices in a main slice memory andthe slice names, access policy, and optionally other informationassociated with the slices in a local virtual DSN address to physicallocation table record such that each is linked to the other forsubsequent simultaneous retrieval. Further examples of access policiesare presented in conjunction with FIGS. 10A-10C.

In various embodiments, a processing system of a dispersed storage andtask (DST) execution unit comprises at least one processor and a memorythat stores operational instructions, that when executed by the at leastone processor, cause the processing system to: receive a slice retrievalrequest from a requester that includes a slice name of one or slices tobe retrieved; determine an access policy to apply to the slice retrievalrequest; determine a timestamp; and determine, based on the timestamp,when the one or more slices are available for retrieval. When the one ormore slices are available for retrieval, the processing system operatesfurther to determine when the one or more slices are currently availableto the requester; retrieves the one or more slices from memory and sendsthe one or more slices to the requester, when the one or more slices arecurrently available to the requester.

In various embodiments, the requester is at least one of: a user, a userdevice, a DST processing unit, a storage integrity processing unit, amanaging unit, or another DST execution unit. The slice retrievalrequest can include one or more of: a requester identifier (ID), acommand, an access policy update, a data object ID, a source name, adata type, a data size indicator, a priority indicator, a securityindicator, or a performance indicator. Determining the access policy toapply to the slice retrieval request can be based on a stored accesspolicy associated with the slice name of the one or more slices.Determining the access policy to apply to the slice retrieval requestcan be based on one or more of a lookup in memory of a previouslyreceived access policy, a requester ID, a command, an access policyupdate, a data object ID, a source name, a data type, a data sizeindicator, a priority indicator, a security indicator, or a performanceindicator.

Determining when the one or more slices are available for retrieval canbe based on one or more of: the access policy, the timestamp, a memorystatus indicator, a DS unit status indicator, or a performanceindicator. The operational instructions, when executed by the at leastone processor, further cause the processing system to: send anunavailable message to the requester when the one or more slices are notavailable for retrieval and/or send an unavailable message to therequester when the one or more slices are not currently available to therequester. These two messages can be formatted the same or differently,for example with differing messages customized to the type ofunavailability. Determining when the one or more slices are currentlyavailable to the requester can be based when the access policy indicatesthat the requester has access authorization at the time indicated by thetimestamp.

FIGS. 10A-10C are schematic block diagrams of embodiments of a dispersedstorage network (DSN) memory storage sets. As illustrated, FIGS. 10A-Crepresent DSN memory storage sets 148-152 (e.g., the set of DS unitsthat store all the pillars of a common data segment) comprising six DSunits 1-6. For example, pillar 1 slices are stored in DS unit 1, pillar2 slices are stored in DS unit 2, pillar 3 slices are stored in DS unit3, pillar 4 slices are stored in DS unit 4, pillar 5 slices are storedin DS unit 5, pillar 6 slices are stored in DS unit 6 when theoperational parameters include a pillar width of n=6 and a readthreshold of 4. As illustrated, FIGS. 10A-C indicate access policypatterns, such as slice availability patterns in accordance with anaccess policy.

As illustrated, FIG. 10A indicates an access policy pattern from thehours of 12:00 AM to 6:00 AM, FIG. 10 B illustrates an access policypattern from the hours of 6:00 AM to 7:00 PM, and FIG. 10 C illustratesan access policy pattern from the hours of 7:00 PM to 12:00 AM. Notethat the access policy pattern may vary second by second, minute byminute, day by day, month-by-month, etc.

Based on these access policy patterns, DS units may read and/or writeslices in vault 1 and/or vault 2 during the specified times of day whenthe particular vault does not include an X. For example, the pillar 2for vault 1 is not available from 12:00 AM to 6:00 AM and the pillar 2for vault 2 is available from 12:00 AM to 6:00 AM as illustrated by FIG.10 A.

Note that the access policy pattern may be utilized to impact datasecurity and performance of the system. For example, the pattern mayenable all of the pillars of a vault to be available in any one or moretime frames to improve system performance. In another example, thepattern may enable just a read threshold of the pillars of a vault to beavailable in any one or more time frames to improve system security butmaintain a moderate level of system performance (e.g., as long as thoseexact pillars remain active). In another example, the pattern may neverenable a read threshold of the pillars of a vault to be available in anysingle time frame to improve system security. In that scenario thepattern may enable a read threshold of the pillars of a vault to beavailable across two or more time frames. As illustrated, vault 1 neverhas a read threshold (e.g., four pillars) number of pillars available inany one of the three time periods. For example, only pillars 4-6 areavailable for vault 1 from 12:00 AM to 6:00 AM, only pillars 1-3 areavailable for vault 1 from 6:00 AM to 7:00 PM, and only pillars 1, 5, 6are available for vault 1 from 7:00 PM to 12:00 AM. As illustrated, thedata segments may be retrieved from vault 1 by access vault 1 across twotimeframes. For example, a DS processing unit may reconstruct a vault 1data segment by retrieving slices of vault 1 from DS units 4-6 duringthe 12:00 AM-6:00 AM timeframe, followed by retrieving slices of vault 1from any one or more of DS units 1-3 during the 6:00 AM-7:00 PMtimeframe.

FIG. 11 is a flowchart illustrating an example of retrieving encodeddata slices. In particular, a method is presented for use in associationwith one or more functions and features described in conjunction withFIGS. 1-10 for execution by a dispersed storage and task (DST) executionunit that includes a processor or via another processing system of adispersed storage network that includes at least one processor andmemory that stores instruction that configure the processor orprocessors to perform the steps described below. Step 108 includesreceiving a slice retrieval request from a requester including any oneof a user device, a DS processing unit, a storage integrity processingunit, a DS managing unit, and another DS unit. The request may includeone or more of a slice name(s), a requester ID, a command, an accesspolicy update, a data object ID, a source name, a data type, a data sizeindicator, a priority indicator, a security indicator, and a performanceindicator.

At step 110, the processing system determines an access policy to applyto the retrieval request based on one or more of a lookup in memory of apreviously received access policy, the slice name(s), the requester ID,a command, an access policy update, a data object ID, a source name, adata type, a data size indicator, a priority indicator, a securityindicator, and performance indicator. For example, the processing systemdetermines the access policy based on the stored access policyassociated with the slice names.

At step 112, the processing system determines a timestamp. For example,the processing system determines the timestamp based on retrieving acurrent time value from a Unix clock (e.g., Unix time, POSIX time) orother hardware or software clock. At step 114, the processing systemdetermines if the requested slice(s) are available based on one or moreof the access policy, the timestamp, a memory status indicator, a DSunit status indicator, and a performance indicator. In an example, theprocessing system determines that the slices are currently unavailablewhen the access policy pattern indicates that no user and/or unitcurrently has access authorization. In another example, the processingsystem determines that the slices are currently available when theaccess policy pattern indicates that at least one user and/or at leastone unit currently has access authorization. The method branches to step118 when the processing system determines that slice(s) are available.The method ends with step 116 when the DS unit determines that slice(s)are not available. At step 116, the processing system sends anunavailable message to the requester such that the requester may tryagain later or give up.

At step 118, the processing system determines if slice(s) are availableto the requester. Such a determination based may be based on one or moreof the access policy, the timestamp, a memory status indicator, a DSunit status indicator, and a performance indicator. For example, theprocessing system determines that the slices are available to therequester when the user ID associated with the requester is listed inthe access policy pattern for the current timestamp. The method branchesto step 122 when the processing system determines that the slice(s) arenot available to the requester. The method continues to step 120 whenthe processing system determines that slice(s) are available. At step120, the processing system retrieves the slice(s) from memory and sendsthe slice(s) to the requester. At step 122, the processing system sendsan unavailable message to the requester when the DS unit determines thatthe slice(s) are not available to the requester.

In various embodiments, a non-transitory computer readable storagemedium includes at least one memory section that stores operationalinstructions that, when executed by a processing system of a dispersedstorage network (DSN) that includes a processor and a memory, causes theprocessing system to receive a slice retrieval request from a requesterthat includes a slice name of one or slices to be retrieved; determinean access policy to apply to the slice retrieval request; determine atimestamp; and determine, based on the timestamp, when the one or moreslices are available for retrieval. When the one or more slices areavailable for retrieval, the processing system operates further todetermine when the one or more slices are currently available to therequester; retrieves the one or more slices from memory and sends theone or more slices to the requester, when the one or more slices arecurrently available to the requester.

It is noted that terminologies as may be used herein such as bit stream,stream, signal sequence, etc. (or their equivalents) have been usedinterchangeably to describe digital information whose contentcorresponds to any of a number of desired types (e.g., data, video,speech, audio, etc. any of which may generally be referred to as‘data’).

As may be used herein, the terms “substantially” and “approximately”provides an industry-accepted tolerance for its corresponding termand/or relativity between items. Such an industry-accepted toleranceranges from less than one percent to fifty percent and corresponds to,but is not limited to, component values, integrated circuit processvariations, temperature variations, rise and fall times, and/or thermalnoise. Such relativity between items ranges from a difference of a fewpercent to magnitude differences. As may also be used herein, theterm(s) “configured to”, “operably coupled to”, “coupled to”, and/or“coupling” includes direct coupling between items and/or indirectcoupling between items via an intervening item (e.g., an item includes,but is not limited to, a component, an element, a circuit, and/or amodule) where, for an example of indirect coupling, the intervening itemdoes not modify the information of a signal but may adjust its currentlevel, voltage level, and/or power level. As may further be used herein,inferred coupling (i.e., where one element is coupled to another elementby inference) includes direct and indirect coupling between two items inthe same manner as “coupled to”. As may even further be used herein, theterm “configured to”, “operable to”, “coupled to”, or “operably coupledto” indicates that an item includes one or more of power connections,input(s), output(s), etc., to perform, when activated, one or more itscorresponding functions and may further include inferred coupling to oneor more other items. As may still further be used herein, the term“associated with”, includes direct and/or indirect coupling of separateitems and/or one item being embedded within another item.

As may be used herein, the term “compares favorably”, indicates that acomparison between two or more items, signals, etc., provides a desiredrelationship. For example, when the desired relationship is that signal1 has a greater magnitude than signal 2, a favorable comparison may beachieved when the magnitude of signal 1 is greater than that of signal 2or when the magnitude of signal 2 is less than that of signal 1. As maybe used herein, the term “compares unfavorably”, indicates that acomparison between two or more items, signals, etc., fails to providethe desired relationship.

As may also be used herein, the terms “processing module”, “processingcircuit”, “processor”, and/or “processing unit” may be a singleprocessing device or a plurality of processing devices. Such aprocessing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, and/or processing unit may be, or furtherinclude, memory and/or an integrated memory element, which may be asingle memory device, a plurality of memory devices, and/or embeddedcircuitry of another processing module, module, processing circuit,and/or processing unit. Such a memory device may be a read-only memory,random access memory, volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module,module, processing circuit, and/or processing unit includes more thanone processing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,and/or processing unit implements one or more of its functions via astate machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory and/or memory element storing the correspondingoperational instructions may be embedded within, or external to, thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry. Still further note that, the memoryelement may store, and the processing module, module, processingcircuit, and/or processing unit executes, hard coded and/or operationalinstructions corresponding to at least some of the steps and/orfunctions illustrated in one or more of the Figures. Such a memorydevice or memory element can be included in an article of manufacture.

One or more embodiments have been described above with the aid of methodsteps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claims. Further, the boundariesof these functional building blocks have been arbitrarily defined forconvenience of description. Alternate boundaries could be defined aslong as the certain significant functions are appropriately performed.Similarly, flow diagram blocks may also have been arbitrarily definedherein to illustrate certain significant functionality.

To the extent used, the flow diagram block boundaries and sequence couldhave been defined otherwise and still perform the certain significantfunctionality. Such alternate definitions of both functional buildingblocks and flow diagram blocks and sequences are thus within the scopeand spirit of the claims. One of average skill in the art will alsorecognize that the functional building blocks, and other illustrativeblocks, modules and components herein, can be implemented as illustratedor by discrete components, application specific integrated circuits,processors executing appropriate software and the like or anycombination thereof.

In addition, a flow diagram may include a “start” and/or “continue”indication. The “start” and “continue” indications reflect that thesteps presented can optionally be incorporated in or otherwise used inconjunction with other routines. In this context, “start” indicates thebeginning of the first step presented and may be preceded by otheractivities not specifically shown. Further, the “continue” indicationreflects that the steps presented may be performed multiple times and/ormay be succeeded by other activities not specifically shown. Further,while a flow diagram indicates a particular ordering of steps, otherorderings are likewise possible provided that the principles ofcausality are maintained.

The one or more embodiments are used herein to illustrate one or moreaspects, one or more features, one or more concepts, and/or one or moreexamples. A physical embodiment of an apparatus, an article ofmanufacture, a machine, and/or of a process may include one or more ofthe aspects, features, concepts, examples, etc. described with referenceto one or more of the embodiments discussed herein. Further, from figureto figure, the embodiments may incorporate the same or similarly namedfunctions, steps, modules, etc. that may use the same or differentreference numbers and, as such, the functions, steps, modules, etc. maybe the same or similar functions, steps, modules, etc. or differentones.

Unless specifically stated to the contra, signals to, from, and/orbetween elements in a figure of any of the figures presented herein maybe analog or digital, continuous time or discrete time, and single-endedor differential. For instance, if a signal path is shown as asingle-ended path, it also represents a differential signal path.Similarly, if a signal path is shown as a differential path, it alsorepresents a single-ended signal path. While one or more particulararchitectures are described herein, other architectures can likewise beimplemented that use one or more data buses not expressly shown, directconnectivity between elements, and/or indirect coupling between otherelements as recognized by one of average skill in the art.

The term “module” is used in the description of one or more of theembodiments. A module implements one or more functions via a device suchas a processor or other processing device or other hardware that mayinclude or operate in association with a memory that stores operationalinstructions. A module may operate independently and/or in conjunctionwith software and/or firmware. As also used herein, a module may containone or more sub-modules, each of which may be one or more modules.

As may further be used herein, a computer readable memory includes oneor more memory elements. A memory element may be a separate memorydevice, multiple memory devices, or a set of memory locations within amemory device. Such a memory device may be a read-only memory, randomaccess memory, volatile memory, non-volatile memory, static memory,dynamic memory, flash memory, cache memory, and/or any device thatstores digital information. The memory device may be in a form a solidstate memory, a hard drive memory, cloud memory, thumb drive, servermemory, computing device memory, and/or other physical medium forstoring digital information.

While particular combinations of various functions and features of theone or more embodiments have been expressly described herein, othercombinations of these features and functions are likewise possible. Thepresent disclosure is not limited by the particular examples disclosedherein and expressly incorporates these other combinations.

What is claimed is:
 1. A method for execution by a dispersed storage andtask (DST) execution unit that includes a processor, the methodcomprises: receiving a slice retrieval request from a requester thatincludes a slice name of one or slices to be retrieved; determining anaccess policy to apply to the slice retrieval request; determining atimestamp; determining, based on the timestamp, when the one or moreslices are available for retrieval; and when the one or more slices areavailable for retrieval: determining when the one or more slices arecurrently available to the requester; and retrieving the one or moreslices from memory and sending the one or more slices to the requester,when the one or more slices are currently available to the requester. 2.The method of claim 1, wherein the requester is at least one of: a user,a user device, a DST processing unit, a storage integrity processingunit, a managing unit, or another DST execution unit.
 3. The method ofclaim 1, wherein the slice retrieval request includes one or more of: arequester identifier (ID), a command, an access policy update, a dataobject ID, a source name, a data type, a data size indicator, a priorityindicator, a security indicator, or a performance indicator.
 4. Themethod of claim 1, wherein determining the access policy to apply to theslice retrieval request is based on a stored access policy associatedwith the slice name of the one or more slices.
 5. The method of claim 1,wherein determining the access policy to apply to the slice retrievalrequest is based on one or more of a lookup in memory of a previouslyreceived access policy, a requester ID, a command, an access policyupdate, a data object ID, a source name, a data type, a data sizeindicator, a priority indicator, a security indicator, or a performanceindicator.
 6. The method of claim 1, wherein determining when the one ormore slices are available for retrieval is based on one or more of: theaccess policy, the timestamp, a memory status indicator, a DS unitstatus indicator, or a performance indicator.
 7. The method of claim 1,further comprising: sending an unavailable message to the requester whenthe one or more slices are not available for retrieval.
 8. The method ofclaim 1, wherein determining when the one or more slices are currentlyavailable to the requester is based when the access policy indicatesthat the requester has access authorization at the time indicated by thetimestamp.
 9. The method of claim 1, further comprising: sending anunavailable message to the requester when the one or more slices are notcurrently available to the requester.
 10. A processing system of adispersed storage and task (DST) execution unit comprises: at least oneprocessor; a memory that stores operational instructions, that whenexecuted by the at least one processor cause the processing system to:receive a slice retrieval request from a requester that includes a slicename of one or slices to be retrieved; determine an access policy toapply to the slice retrieval request; determine a timestamp; determine,based on the timestamp, when the one or more slices are available forretrieval; and when the one or more slices are available for retrieval:determine when the one or more slices are currently available to therequester; and retrieve the one or more slices from memory and send theone or more slices to the requester, when the one or more slices arecurrently available to the requester.
 11. The processing system of claim10, wherein the requester is at least one of: a user, a user device, aDST processing unit, a storage integrity processing unit, a managingunit, or another DST execution unit.
 12. The processing system of claim10, wherein the slice retrieval request includes one or more of: arequester identifier (ID), a command, an access policy update, a dataobject ID, a source name, a data type, a data size indicator, a priorityindicator, a security indicator, or a performance indicator.
 13. Theprocessing system of claim 10, wherein determining the access policy toapply to the slice retrieval request is based on a stored access policyassociated with the slice name of the one or more slices.
 14. Theprocessing system of claim 10, wherein determining the access policy toapply to the slice retrieval request is based on one or more of a lookupin memory of a previously received access policy, a requester ID, acommand, an access policy update, a data object ID, a source name, adata type, a data size indicator, a priority indicator, a securityindicator, or a performance indicator.
 15. The processing system ofclaim 10, wherein determining when the one or more slices are availablefor retrieval is based on one or more of: the access policy, thetimestamp, a memory status indicator, a DS unit status indicator, or aperformance indicator.
 16. The processing system of claim 10, whereinthe operational instructions, when executed by the at least oneprocessor, further cause the processing system to: send an unavailablemessage to the requester when the one or more slices are not availablefor retrieval.
 17. The processing system of claim 10, whereindetermining when the one or more slices are currently available to therequester is based when the access policy indicates that the requesterhas access authorization at the time indicated by the timestamp.
 18. Theprocessing system of claim 10, wherein the operational instructions,when executed by the at least one processor, further cause theprocessing system to: send an unavailable message to the requester whenthe one or more slices are not currently available to the requester. 19.A non-transitory computer readable storage medium comprises: at leastone memory section that stores operational instructions that, whenexecuted by a processing system of a dispersed storage network (DSN)that includes a processor and a memory, causes the processing system to:receive a slice retrieval request from a requester that includes a slicename of one or slices to be retrieved; determine an access policy toapply to the slice retrieval request; determine a timestamp; determine,based on the timestamp, when the one or more slices are available forretrieval; and when the one or more slices are available for retrieval:determine when the one or more slices are currently available to therequester; and retrieve the one or more slices from memory and send theone or more slices to the requester, when the one or more slices arecurrently available to the requester.
 20. The non-transitory computerreadable storage medium of claim 19, wherein determining the accesspolicy to apply to the slice retrieval request is based on a storedaccess policy associated with the slice name of the one or more slices.